Figure 1
From: Ethical challenges with the left ventricular assist device as a destination therapy
The left ventricular assist device (LVAD). The LVAD from Thoratec Corporation (Pleasanton, California), the HeartMate LVAS (left ventricular assist system) XVE, helps the left ventricle of the heart pump blood throughout the body. A median sternotomy and cardiopulmonary bypass are required for access and implantation of the LVAD. The LVAD is implanted below the heart within the abdominal wall or peritoneal cavity. The LVAD is attached in parallel with the cardiovascular system. This leaves the heart connected to the circulatory system but provides the energy needed to propel blood throughout the body. The inflow cannula is anastomosed to the tip of the left ventricle so that blood is channeled into the device. An external control system triggers blood from the natural heart to fill the pump. A small motor drives the pump through an external battery-powered control unit. A pusher plate forces a flexible polyurethane diaphragm upward and pressurizes the blood chamber. This motion propels blood through an outflow conduit and a graft that is attached to the ascending aorta. The ascending aorta is the main artery supplying oxygen-rich blood throughout the body. Valves located on either side of the pumping chamber of the device keep blood flowing in one direction only. For more information, see Thoratec Web site[1]. (From http://www.heartfailure.org. [Used with permission.]). See Supplemental file for Uniform Resource Locator (URL) links for videos on implantation procedures of ventricular assist devices.